The Cassini spacecraft was launched on October 15, 1997 from Cape Canaveral Air Force Station using a U.S. Air Force Titan IVB/Centaur launch vehicle. The launch vehicle was made up of a two-stage Titan IV booster rocket, two strap-on solid rocket motors, the Centaur upper stage, and a payload enclosure or fairing. The complete Cassini flight system was composed of the launch vehicle and the spacecraft. The spacecraft, in turn, is composed of the orbiter and the Huygens probe.

The Cassini spacecraft, including the orbiter and the Huygens probe, is one of the largest, heaviest, and most complex interplanetary spacecraft ever built. The orbiter alone weighs 2,150 kilograms (4,750 pounds). When the 350-kilogram Huygens probe, launch vehicle adapter, and 3,132 kilograms (6,905 pounds) of propellants were loaded, the spacecraft weighed about 5,600 kilograms (12,346 pounds) at launch. Only the two Phobos spacecraft sent to Mars by the former Soviet Union were heavier. The Cassini spacecraft stood more than 6.8 meters (22.3 feet) high and was more than 4 meters (13.1 feet) wide. The complexity of the spacecraft is necessitated both by its trajectory or flight path to Saturn and by the ambitious program of scientific observations to be undertaken once the spacecraft reaches its destination. It will function with 1,630 interconnect circuits, 22,000 wire connections, and over 14 kilometers (8.7 miles) of cabling.

You might well ask "why is the spacecraft being built in the first place?" A space mission such as Cassini begins with a set of science goals that the scientific community, and much of society wants to achieve. In this case, we are hoping to obtain a better understanding of the planet Saturn, its famous rings, its magnetosphere, its principal moon Titan, and its other moons or "icy satellites." There are also many other benefits, including technology spin-offs, international cooperation, and educational motivation for people of all ages.